DESCRIPTION: Polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorinated dibenzo-dioxin (TCDD) are neurodevelopmental and immunologic toxicants in experimental animals treated prenatally. Associations with neurobehavioural deficits are found in some but not all epidemiologic studies of environmental exposures, with data suggesting the prenatal period to be the most sensitive. Additionally, the risk of intrauterine growth retardation increases with higher environmental PCB exposures, and several reports suggest a more potent effect in male babies. The proposed study will therefore evaluate prenatal and postnatal PCB and dioxin exposures in relation to immune markers at birth and in early childhood, to intrauterine and early childhood growth, and to early neurobehavioral development. It will be conducted in the Slovak Republic, where a chemical plant that manufactured PCBs improperly discharged large quantitites of contaminated waste into the surrounding area. A total of 1200 births in years 2001-2003 will be enrolled in two districts, half from the district with high contamination of PCBs, and the other half from a district with lower contamination levels. The study will parallel a European Union-funded study of adults and school-age children in the same two districts. The project will be one of the first to evaluate a wide battery of immune parameters in an epidemiologic study, including lymphocyte immunophenotypes, thymic size, post-vaccination antibody titers, aand morbidity. It will also be the largest to-dat to evlaute neurobehavioral development. Other unique features include the evaluation of hearing loss at birth, the measurement of hydroxy and methylsulfone metabolites of PCBs, and a population which includes about 1/3 Gypsies.